It seems likely that the biological consequences of radiation exposure are the result of sequences of biochemical processes initiated by the chemical changes caused by energy deposited as ionization or excitation. Based on this assumption, it would appear that a detailed knowledge of the energy deposited in relevant biological targets would provide a basis for predicting the biological risk. However, there is generally insufficient knowledge of the biological processes for such predictions to be successful. However, knowledge of energy deposition characteristics can help to determine if specific models of biological processes are tenable. Furthermore, an alternative to absorbed dose may provide a way to characterize the energy deposition, which is more easily related to the health risk and less likely to be misconstrued when used to describe low levels of radiation exposure. Some examples of limits on models and alternatives to absorbed dose are described.
